This invention relates to the use of invertebrate growth regulators, neurohormones, and other invertebrate endocrine products as vaccine components to actively immunize a vertebrate against ectoparasites and endoparasites, and as medicaments to treat a vertebrate infected by said parasites.
Conventional attempts to prevent, or rid a host of, infection by ectoparasites and endoparasites (hereinafter also referred to as target parasites) have involved treatment of a susceptible or infected host (e.g., mammal) with anthelmintic chemicals [see generally, Goodman and Gilman's, The Pharmacologicol Basis of Therapeutics, 6th Ed., pp. 1013-79 (1980)]. For example, U.S. Pat. No. 3,746,490 refers to a method for controlling instar bot larvae and endoparasites in horses comprising applying a paste containing dimethyl-1-dichlorovinyl phosphate into the mouth of a horse; U.S. Pat. No. 3,879,533 refers to the control of endoparasitic nematodes by 3-phenyl-5-(halo-, alkylthio- or alkoxy)-isoxazoles; U.S. Pat. No. 4,036,987 refers to the control of nematodes and other helminths using secondary and tertiary straight end branched chain amides and amines; and U.S. Pat. No. 4,374,853 refers to a method for controlling mammalian ectoparasites, such as fleas and ticks, using an aqueous antiseptic liquid. Typically these treatments are characterized by various undesirable side effects, such as short periods of sensitivity, toxic build-up of chemicals, a need to re-treat animals and the development of resistance to chemicals by the targetted parasites.
In view of the disadvantages of such therapies, various other methods of protecting mammals from ectoparasitic and endoparasitic infection have been attempted. For example, U.S. Pat. No. 3,395,218 refers to a method of immunization using nematode surface antigens formed from the ex-sheathment of larvae. More recently, attempts have been made to use ecdysone or juvenile hormones and their analogues to disrupt directly the development of helminth endoparasites. For example, when juvenile hormones are administered to the infected host during metamorphosis (larvae into adult) the adult endoparasites produced are deformed and lack the capacity for further development and soon die [see generally, Van Nostrand's Scientific Encyclopedia, 6th Ed. pp. 1620-25 (1983); F. W. Douvres et al., "In Vitro Cultivation Of Ostertagia ostertagi, The Medium Stomach Worms Of Cattle. II. Effect of Insect-Growth-Disrupting Amines And Amides On Development," Veterinary Parasitology, 1, pp. 195-205 (1980); G. H. Glassburg et al., "Juvenoid effects on Nippostrongylus brasiliensis and Heterodera glycines (Nematoda)," Proc. Helm. Soc. Wash., 50, pp. 62-68 (1983)]. However, such treatment is not very reliable because effectiveness is limited to the relatively short period of metamorphosis; if the juvenile hormones are applied before or after this period, they are ineffective. Furthermore, such treatment would have to be repeated frequently and, because of inefficient tissue distribution in the infected host, may not even reach and be absorbed by the infected tissue.